Reapply Logging: make os_log buffer size an integer constant expression.

The size of an os_log buffer is known at any stage of compilation, so making it
a constant expression means that the common idiom of declaring a buffer for it
won't result in a VLA. That allows the compiler to skip saving and restoring
the stack pointer around such buffers.

This also moves the OSLog and other FormatString helpers from
libclangAnalysis to libclangAST to avoid a circular dependency.

llvm-svn: 345971

1 files changed, 563 insertions, 0 deletions

diff --git a/clang/lib/AST/ScanfFormatString.cpp b/clang/lib/AST/ScanfFormatString.cpp
new file mode 100644
index 00000000000..bda97c57c87
--- /dev/null
+++ b/clang/lib/AST/ScanfFormatString.cpp
@@ -0,0 +1,563 @@
+//= ScanfFormatString.cpp - Analysis of printf format strings --*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Handling of format string in scanf and friends.  The structure of format
+// strings for fscanf() are described in C99 7.19.6.2.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/AST/FormatString.h"
+#include "FormatStringParsing.h"
+#include "clang/Basic/TargetInfo.h"
+
+using clang::analyze_format_string::ArgType;
+using clang::analyze_format_string::FormatStringHandler;
+using clang::analyze_format_string::LengthModifier;
+using clang::analyze_format_string::OptionalAmount;
+using clang::analyze_format_string::ConversionSpecifier;
+using clang::analyze_scanf::ScanfConversionSpecifier;
+using clang::analyze_scanf::ScanfSpecifier;
+using clang::UpdateOnReturn;
+using namespace clang;
+
+typedef clang::analyze_format_string::SpecifierResult<ScanfSpecifier>
+        ScanfSpecifierResult;
+
+static bool ParseScanList(FormatStringHandler &H,
+                          ScanfConversionSpecifier &CS,
+                          const char *&Beg, const char *E) {
+  const char *I = Beg;
+  const char *start = I - 1;
+  UpdateOnReturn <const char*> UpdateBeg(Beg, I);
+
+  // No more characters?
+  if (I == E) {
+    H.HandleIncompleteScanList(start, I);
+    return true;
+  }
+
+  // Special case: ']' is the first character.
+  if (*I == ']') {
+    if (++I == E) {
+      H.HandleIncompleteScanList(start, I - 1);
+      return true;
+    }
+  }
+
+  // Special case: "^]" are the first characters.
+  if (I + 1 != E && I[0] == '^' && I[1] == ']') {
+    I += 2;
+    if (I == E) {
+      H.HandleIncompleteScanList(start, I - 1);
+      return true;
+    }
+  }
+
+  // Look for a ']' character which denotes the end of the scan list.
+  while (*I != ']') {
+    if (++I == E) {
+      H.HandleIncompleteScanList(start, I - 1);
+      return true;
+    }
+  }
+
+  CS.setEndScanList(I);
+  return false;
+}
+
+// FIXME: Much of this is copy-paste from ParsePrintfSpecifier.
+// We can possibly refactor.
+static ScanfSpecifierResult ParseScanfSpecifier(FormatStringHandler &H,
+                                                const char *&Beg,
+                                                const char *E,
+                                                unsigned &argIndex,
+                                                const LangOptions &LO,
+                                                const TargetInfo &Target) {
+  using namespace clang::analyze_format_string;
+  using namespace clang::analyze_scanf;
+  const char *I = Beg;
+  const char *Start = nullptr;
+  UpdateOnReturn <const char*> UpdateBeg(Beg, I);
+
+    // Look for a '%' character that indicates the start of a format specifier.
+  for ( ; I != E ; ++I) {
+    char c = *I;
+    if (c == '\0') {
+        // Detect spurious null characters, which are likely errors.
+      H.HandleNullChar(I);
+      return true;
+    }
+    if (c == '%') {
+      Start = I++;  // Record the start of the format specifier.
+      break;
+    }
+  }
+
+    // No format specifier found?
+  if (!Start)
+    return false;
+
+  if (I == E) {
+      // No more characters left?
+    H.HandleIncompleteSpecifier(Start, E - Start);
+    return true;
+  }
+
+  ScanfSpecifier FS;
+  if (ParseArgPosition(H, FS, Start, I, E))
+    return true;
+
+  if (I == E) {
+      // No more characters left?
+    H.HandleIncompleteSpecifier(Start, E - Start);
+    return true;
+  }
+
+  // Look for '*' flag if it is present.
+  if (*I == '*') {
+    FS.setSuppressAssignment(I);
+    if (++I == E) {
+      H.HandleIncompleteSpecifier(Start, E - Start);
+      return true;
+    }
+  }
+
+  // Look for the field width (if any).  Unlike printf, this is either
+  // a fixed integer or isn't present.
+  const OptionalAmount &Amt = clang::analyze_format_string::ParseAmount(I, E);
+  if (Amt.getHowSpecified() != OptionalAmount::NotSpecified) {
+    assert(Amt.getHowSpecified() == OptionalAmount::Constant);
+    FS.setFieldWidth(Amt);
+
+    if (I == E) {
+      // No more characters left?
+      H.HandleIncompleteSpecifier(Start, E - Start);
+      return true;
+    }
+  }
+
+  // Look for the length modifier.
+  if (ParseLengthModifier(FS, I, E, LO, /*scanf=*/true) && I == E) {
+      // No more characters left?
+    H.HandleIncompleteSpecifier(Start, E - Start);
+    return true;
+  }
+
+  // Detect spurious null characters, which are likely errors.
+  if (*I == '\0') {
+    H.HandleNullChar(I);
+    return true;
+  }
+
+  // Finally, look for the conversion specifier.
+  const char *conversionPosition = I++;
+  ScanfConversionSpecifier::Kind k = ScanfConversionSpecifier::InvalidSpecifier;
+  switch (*conversionPosition) {
+    default:
+      break;
+    case '%': k = ConversionSpecifier::PercentArg;   break;
+    case 'A': k = ConversionSpecifier::AArg; break;
+    case 'E': k = ConversionSpecifier::EArg; break;
+    case 'F': k = ConversionSpecifier::FArg; break;
+    case 'G': k = ConversionSpecifier::GArg; break;
+    case 'X': k = ConversionSpecifier::XArg; break;
+    case 'a': k = ConversionSpecifier::aArg; break;
+    case 'd': k = ConversionSpecifier::dArg; break;
+    case 'e': k = ConversionSpecifier::eArg; break;
+    case 'f': k = ConversionSpecifier::fArg; break;
+    case 'g': k = ConversionSpecifier::gArg; break;
+    case 'i': k = ConversionSpecifier::iArg; break;
+    case 'n': k = ConversionSpecifier::nArg; break;
+    case 'c': k = ConversionSpecifier::cArg; break;
+    case 'C': k = ConversionSpecifier::CArg; break;
+    case 'S': k = ConversionSpecifier::SArg; break;
+    case '[': k = ConversionSpecifier::ScanListArg; break;
+    case 'u': k = ConversionSpecifier::uArg; break;
+    case 'x': k = ConversionSpecifier::xArg; break;
+    case 'o': k = ConversionSpecifier::oArg; break;
+    case 's': k = ConversionSpecifier::sArg; break;
+    case 'p': k = ConversionSpecifier::pArg; break;
+    // Apple extensions
+      // Apple-specific
+    case 'D':
+      if (Target.getTriple().isOSDarwin())
+        k = ConversionSpecifier::DArg;
+      break;
+    case 'O':
+      if (Target.getTriple().isOSDarwin())
+        k = ConversionSpecifier::OArg;
+      break;
+    case 'U':
+      if (Target.getTriple().isOSDarwin())
+        k = ConversionSpecifier::UArg;
+      break;
+  }
+  ScanfConversionSpecifier CS(conversionPosition, k);
+  if (k == ScanfConversionSpecifier::ScanListArg) {
+    if (ParseScanList(H, CS, I, E))
+      return true;
+  }
+  FS.setConversionSpecifier(CS);
+  if (CS.consumesDataArgument() && !FS.getSuppressAssignment()
+      && !FS.usesPositionalArg())
+    FS.setArgIndex(argIndex++);
+
+  // FIXME: '%' and '*' doesn't make sense.  Issue a warning.
+  // FIXME: 'ConsumedSoFar' and '*' doesn't make sense.
+
+  if (k == ScanfConversionSpecifier::InvalidSpecifier) {
+    unsigned Len = I - Beg;
+    if (ParseUTF8InvalidSpecifier(Beg, E, Len)) {
+      CS.setEndScanList(Beg + Len);
+      FS.setConversionSpecifier(CS);
+    }
+    // Assume the conversion takes one argument.
+    return !H.HandleInvalidScanfConversionSpecifier(FS, Beg, Len);
+  }
+  return ScanfSpecifierResult(Start, FS);
+}
+
+ArgType ScanfSpecifier::getArgType(ASTContext &Ctx) const {
+  const ScanfConversionSpecifier &CS = getConversionSpecifier();
+
+  if (!CS.consumesDataArgument())
+    return ArgType::Invalid();
+
+  switch(CS.getKind()) {
+    // Signed int.
+    case ConversionSpecifier::dArg:
+    case ConversionSpecifier::DArg:
+    case ConversionSpecifier::iArg:
+      switch (LM.getKind()) {
+        case LengthModifier::None:
+          return ArgType::PtrTo(Ctx.IntTy);
+        case LengthModifier::AsChar:
+          return ArgType::PtrTo(ArgType::AnyCharTy);
+        case LengthModifier::AsShort:
+          return ArgType::PtrTo(Ctx.ShortTy);
+        case LengthModifier::AsLong:
+          return ArgType::PtrTo(Ctx.LongTy);
+        case LengthModifier::AsLongLong:
+        case LengthModifier::AsQuad:
+          return ArgType::PtrTo(Ctx.LongLongTy);
+        case LengthModifier::AsInt64:
+          return ArgType::PtrTo(ArgType(Ctx.LongLongTy, "__int64"));
+        case LengthModifier::AsIntMax:
+          return ArgType::PtrTo(ArgType(Ctx.getIntMaxType(), "intmax_t"));
+        case LengthModifier::AsSizeT:
+          return ArgType::PtrTo(ArgType(Ctx.getSignedSizeType(), "ssize_t"));
+        case LengthModifier::AsPtrDiff:
+          return ArgType::PtrTo(ArgType(Ctx.getPointerDiffType(), "ptrdiff_t"));
+        case LengthModifier::AsLongDouble:
+          // GNU extension.
+          return ArgType::PtrTo(Ctx.LongLongTy);
+        case LengthModifier::AsAllocate:
+        case LengthModifier::AsMAllocate:
+        case LengthModifier::AsInt32:
+        case LengthModifier::AsInt3264:
+        case LengthModifier::AsWide:
+          return ArgType::Invalid();
+      }
+
+    // Unsigned int.
+    case ConversionSpecifier::oArg:
+    case ConversionSpecifier::OArg:
+    case ConversionSpecifier::uArg:
+    case ConversionSpecifier::UArg:
+    case ConversionSpecifier::xArg:
+    case ConversionSpecifier::XArg:
+      switch (LM.getKind()) {
+        case LengthModifier::None:
+          return ArgType::PtrTo(Ctx.UnsignedIntTy);
+        case LengthModifier::AsChar:
+          return ArgType::PtrTo(Ctx.UnsignedCharTy);
+        case LengthModifier::AsShort:
+          return ArgType::PtrTo(Ctx.UnsignedShortTy);
+        case LengthModifier::AsLong:
+          return ArgType::PtrTo(Ctx.UnsignedLongTy);
+        case LengthModifier::AsLongLong:
+        case LengthModifier::AsQuad:
+          return ArgType::PtrTo(Ctx.UnsignedLongLongTy);
+        case LengthModifier::AsInt64:
+          return ArgType::PtrTo(ArgType(Ctx.UnsignedLongLongTy, "unsigned __int64"));
+        case LengthModifier::AsIntMax:
+          return ArgType::PtrTo(ArgType(Ctx.getUIntMaxType(), "uintmax_t"));
+        case LengthModifier::AsSizeT:
+          return ArgType::PtrTo(ArgType(Ctx.getSizeType(), "size_t"));
+        case LengthModifier::AsPtrDiff:
+          return ArgType::PtrTo(
+              ArgType(Ctx.getUnsignedPointerDiffType(), "unsigned ptrdiff_t"));
+        case LengthModifier::AsLongDouble:
+          // GNU extension.
+          return ArgType::PtrTo(Ctx.UnsignedLongLongTy);
+        case LengthModifier::AsAllocate:
+        case LengthModifier::AsMAllocate:
+        case LengthModifier::AsInt32:
+        case LengthModifier::AsInt3264:
+        case LengthModifier::AsWide:
+          return ArgType::Invalid();
+      }
+
+    // Float.
+    case ConversionSpecifier::aArg:
+    case ConversionSpecifier::AArg:
+    case ConversionSpecifier::eArg:
+    case ConversionSpecifier::EArg:
+    case ConversionSpecifier::fArg:
+    case ConversionSpecifier::FArg:
+    case ConversionSpecifier::gArg:
+    case ConversionSpecifier::GArg:
+      switch (LM.getKind()) {
+        case LengthModifier::None:
+          return ArgType::PtrTo(Ctx.FloatTy);
+        case LengthModifier::AsLong:
+          return ArgType::PtrTo(Ctx.DoubleTy);
+        case LengthModifier::AsLongDouble:
+          return ArgType::PtrTo(Ctx.LongDoubleTy);
+        default:
+          return ArgType::Invalid();
+      }
+
+    // Char, string and scanlist.
+    case ConversionSpecifier::cArg:
+    case ConversionSpecifier::sArg:
+    case ConversionSpecifier::ScanListArg:
+      switch (LM.getKind()) {
+        case LengthModifier::None:
+          return ArgType::PtrTo(ArgType::AnyCharTy);
+        case LengthModifier::AsLong:
+        case LengthModifier::AsWide:
+          return ArgType::PtrTo(ArgType(Ctx.getWideCharType(), "wchar_t"));
+        case LengthModifier::AsAllocate:
+        case LengthModifier::AsMAllocate:
+          return ArgType::PtrTo(ArgType::CStrTy);
+        case LengthModifier::AsShort:
+          if (Ctx.getTargetInfo().getTriple().isOSMSVCRT())
+            return ArgType::PtrTo(ArgType::AnyCharTy);
+          LLVM_FALLTHROUGH;
+        default:
+          return ArgType::Invalid();
+      }
+    case ConversionSpecifier::CArg:
+    case ConversionSpecifier::SArg:
+      // FIXME: Mac OS X specific?
+      switch (LM.getKind()) {
+        case LengthModifier::None:
+        case LengthModifier::AsWide:
+          return ArgType::PtrTo(ArgType(Ctx.getWideCharType(), "wchar_t"));
+        case LengthModifier::AsAllocate:
+        case LengthModifier::AsMAllocate:
+          return ArgType::PtrTo(ArgType(ArgType::WCStrTy, "wchar_t *"));
+        case LengthModifier::AsShort:
+          if (Ctx.getTargetInfo().getTriple().isOSMSVCRT())
+            return ArgType::PtrTo(ArgType::AnyCharTy);
+          LLVM_FALLTHROUGH;
+        default:
+          return ArgType::Invalid();
+      }
+
+    // Pointer.
+    case ConversionSpecifier::pArg:
+      return ArgType::PtrTo(ArgType::CPointerTy);
+
+    // Write-back.
+    case ConversionSpecifier::nArg:
+      switch (LM.getKind()) {
+        case LengthModifier::None:
+          return ArgType::PtrTo(Ctx.IntTy);
+        case LengthModifier::AsChar:
+          return ArgType::PtrTo(Ctx.SignedCharTy);
+        case LengthModifier::AsShort:
+          return ArgType::PtrTo(Ctx.ShortTy);
+        case LengthModifier::AsLong:
+          return ArgType::PtrTo(Ctx.LongTy);
+        case LengthModifier::AsLongLong:
+        case LengthModifier::AsQuad:
+          return ArgType::PtrTo(Ctx.LongLongTy);
+        case LengthModifier::AsInt64:
+          return ArgType::PtrTo(ArgType(Ctx.LongLongTy, "__int64"));
+        case LengthModifier::AsIntMax:
+          return ArgType::PtrTo(ArgType(Ctx.getIntMaxType(), "intmax_t"));
+        case LengthModifier::AsSizeT:
+          return ArgType::PtrTo(ArgType(Ctx.getSignedSizeType(), "ssize_t"));
+        case LengthModifier::AsPtrDiff:
+          return ArgType::PtrTo(ArgType(Ctx.getPointerDiffType(), "ptrdiff_t"));
+        case LengthModifier::AsLongDouble:
+          return ArgType(); // FIXME: Is this a known extension?
+        case LengthModifier::AsAllocate:
+        case LengthModifier::AsMAllocate:
+        case LengthModifier::AsInt32:
+        case LengthModifier::AsInt3264:
+        case LengthModifier::AsWide:
+          return ArgType::Invalid();
+        }
+
+    default:
+      break;
+  }
+
+  return ArgType();
+}
+
+bool ScanfSpecifier::fixType(QualType QT, QualType RawQT,
+                             const LangOptions &LangOpt,
+                             ASTContext &Ctx) {
+
+  // %n is different from other conversion specifiers; don't try to fix it.
+  if (CS.getKind() == ConversionSpecifier::nArg)
+    return false;
+
+  if (!QT->isPointerType())
+    return false;
+
+  QualType PT = QT->getPointeeType();
+
+  // If it's an enum, get its underlying type.
+  if (const EnumType *ETy = PT->getAs<EnumType>()) {
+    // Don't try to fix incomplete enums.
+    if (!ETy->getDecl()->isComplete())
+      return false;
+    PT = ETy->getDecl()->getIntegerType();
+  }
+
+  const BuiltinType *BT = PT->getAs<BuiltinType>();
+  if (!BT)
+    return false;
+
+  // Pointer to a character.
+  if (PT->isAnyCharacterType()) {
+    CS.setKind(ConversionSpecifier::sArg);
+    if (PT->isWideCharType())
+      LM.setKind(LengthModifier::AsWideChar);
+    else
+      LM.setKind(LengthModifier::None);
+
+    // If we know the target array length, we can use it as a field width.
+    if (const ConstantArrayType *CAT = Ctx.getAsConstantArrayType(RawQT)) {
+      if (CAT->getSizeModifier() == ArrayType::Normal)
+        FieldWidth = OptionalAmount(OptionalAmount::Constant,
+                                    CAT->getSize().getZExtValue() - 1,
+                                    "", 0, false);
+
+    }
+    return true;
+  }
+
+  // Figure out the length modifier.
+  switch (BT->getKind()) {
+    // no modifier
+    case BuiltinType::UInt:
+    case BuiltinType::Int:
+    case BuiltinType::Float:
+      LM.setKind(LengthModifier::None);
+      break;
+
+    // hh
+    case BuiltinType::Char_U:
+    case BuiltinType::UChar:
+    case BuiltinType::Char_S:
+    case BuiltinType::SChar:
+      LM.setKind(LengthModifier::AsChar);
+      break;
+
+    // h
+    case BuiltinType::Short:
+    case BuiltinType::UShort:
+      LM.setKind(LengthModifier::AsShort);
+      break;
+
+    // l
+    case BuiltinType::Long:
+    case BuiltinType::ULong:
+    case BuiltinType::Double:
+      LM.setKind(LengthModifier::AsLong);
+      break;
+
+    // ll
+    case BuiltinType::LongLong:
+    case BuiltinType::ULongLong:
+      LM.setKind(LengthModifier::AsLongLong);
+      break;
+
+    // L
+    case BuiltinType::LongDouble:
+      LM.setKind(LengthModifier::AsLongDouble);
+      break;
+
+    // Don't know.
+    default:
+      return false;
+  }
+
+  // Handle size_t, ptrdiff_t, etc. that have dedicated length modifiers in C99.
+  if (isa<TypedefType>(PT) && (LangOpt.C99 || LangOpt.CPlusPlus11))
+    namedTypeToLengthModifier(PT, LM);
+
+  // If fixing the length modifier was enough, we are done.
+  if (hasValidLengthModifier(Ctx.getTargetInfo())) {
+    const analyze_scanf::ArgType &AT = getArgType(Ctx);
+    if (AT.isValid() && AT.matchesType(Ctx, QT))
+      return true;
+  }
+
+  // Figure out the conversion specifier.
+  if (PT->isRealFloatingType())
+    CS.setKind(ConversionSpecifier::fArg);
+  else if (PT->isSignedIntegerType())
+    CS.setKind(ConversionSpecifier::dArg);
+  else if (PT->isUnsignedIntegerType())
+    CS.setKind(ConversionSpecifier::uArg);
+  else
+    llvm_unreachable("Unexpected type");
+
+  return true;
+}
+
+void ScanfSpecifier::toString(raw_ostream &os) const {
+  os << "%";
+
+  if (usesPositionalArg())
+    os << getPositionalArgIndex() << "$";
+  if (SuppressAssignment)
+    os << "*";
+
+  FieldWidth.toString(os);
+  os << LM.toString();
+  os << CS.toString();
+}
+
+bool clang::analyze_format_string::ParseScanfString(FormatStringHandler &H,
+                                                    const char *I,
+                                                    const char *E,
+                                                    const LangOptions &LO,
+                                                    const TargetInfo &Target) {
+
+  unsigned argIndex = 0;
+
+  // Keep looking for a format specifier until we have exhausted the string.
+  while (I != E) {
+    const ScanfSpecifierResult &FSR = ParseScanfSpecifier(H, I, E, argIndex,
+                                                          LO, Target);
+    // Did a fail-stop error of any kind occur when parsing the specifier?
+    // If so, don't do any more processing.
+    if (FSR.shouldStop())
+      return true;
+      // Did we exhaust the string or encounter an error that
+      // we can recover from?
+    if (!FSR.hasValue())
+      continue;
+      // We have a format specifier.  Pass it to the callback.
+    if (!H.HandleScanfSpecifier(FSR.getValue(), FSR.getStart(),
+                                I - FSR.getStart())) {
+      return true;
+    }
+  }
+  assert(I == E && "Format string not exhausted");
+  return false;
+}